Only if you move the whole BOINC Data directory, with all files and sub-directories in it, and:
1. The OS is of the same class. Windows to Windows, not Windows to Linux.
2. The bitrate is the same. 32bit to 32bit, not 64bit to 32bit.
3. You never let the old PC contact Seti again under this hostID account.
____________Jord

If you have not found the file client_state.xml, you have NOT found the BOINC Data directory. One of the directories in the path to the Data directory is hidden by default, and the location of the data directory shows in the first few messages after a restart of BOINC.
____________BOINC WIKI